I hope you are aware that the ROS 2 alpha 8 version (of this thread) has been superseded by several new versions. So you might want to make sure to build on top of the latest release which is ROS Crystal.
It would be good to point to specific code snippets when making a statement like that to clarify what exactly you are referring to.
Also any DDS specific API usage is encapsulated in the RMW implementation for that specific vendor. So each RMW implementation chooses how it wants to implement the RMW interface. If you think some of the implementation could be updated please feel free to fill a ticket (or even better a pull request) in the corresponding repository.